Immunology Tests
Blood investigations are often requested at initial and follow up appointments; these provide important information to guide diagnosis and further management.
General blood tests include full blood count, kidney and liver function tests, inflammatory marker (for example C-Reactive Protein (CRP)) and lipid profile, are often requested, as well as other investigations to monitor treatment side effects or for complications.
What are White blood cells?
White blood cells help our body to fight disease-causing bugs. There are different types of white blood cells, and they all have their unique strength and method of fighting infection. Examples include neutrophils, eosinophils, lymphocytes ( T cells, B cells and natural killer cells).
What are T cells & B cells?
T cells and B cells are specific subtypes of white blood cells. B cells are known for their ability to produce antibodies. T cells fight infections and help B cells make good quality antibodies that work against disease-causing bugs.
I see ‘CD+ a number’ on my blood test results, for example CD 19, CD3. What are they?
“CD + number” is the “name badge” for different types of white blood cells. Each type of white blood cell has its unique identification markers called “CD markers” on the surfaces. For example, B cells’ primary identification marker is called “CD19”, whereas “CD3” is the main marker for T cells.
Our laboratory uses these cell markers or “name badges” to categorise and count the white blood cells. These tests tell us if your body has the usual numbers of each specific type of white blood cells, so that we can understand your immune system better. If these tests are used, your immunologist will be able to discuss the results with you in more detail and answer any questions.
What are immunoglobulins (antibodies)?
Immunoglobulin is a medical term for “antibody”. Antibodies are proteins produced by B cells to help fight infections. There are different types of antibodies and some of the common examples are IgG, IgA, IgM and IgE. Each type of antibody has its own character and style of fighting infections in our body. Our body can have a low antibody level for numerous reasons, including problems with the immune system. If this is suspected, your immunology doctor may request further tests.
What are complement proteins?
Complement proteins are a group of blood proteins that are involved in helping fight bacterial infections, particularly bugs that can infect the lining of your brain (meningitis). They are called complement proteins because they complement the other parts of the immune system, and work together with the rest of your immune system. They also have an important role in clearing dead or dying cells in our bodies.
What is the DHR test (Dihydrorhodamine reductase)?
Neutrophils are white blood cells that kill invading bugs by “swallowing” and “digesting” them. The DHR test helps us to understand how well neutrophils are working. In a rare genetic condition called chronic granulomatous disease, neutrophils are unable to “digest” the invading bugs and, therefore, unable to get rid of them.
What are the vaccine studies for?
Immunologists often use vaccine studies to understand how well your immune system can respond to vaccines. This may involve giving you a vaccine and/or arranging a blood test to check if you responded to the vaccine. Checking this helps us to understand which part of your immune system is working or not working well. Commonly used vaccines for this testing include pneumococcus, Haemophilus influenzae type B, meningococcus, tetanus.
What is Mast cell tryptase?
Mast cell tryptase is an enzyme found inside mast cells and can be released into your blood when the mast cells become activated. Mast cells are the cells that become active during an allergic reaction. We sometime refer to mast cells as “allergy cells”. Mast cell tryptase is a useful test that can indicate how active your “allergy cells” were during a reaction. We need to measure the mast cell tryptase during a reaction and when you are not having a reaction to see if the levels are different. A higher level during a reaction suggests the mast cell was activated at the time.
IgE and Specific IgE antibody
IgE antibodies are a type of antibody that are involved in allergy. Specific IgE antibodies refer to IgE antibodies that bind to something specific (for example penicillin, peanut, grass pollen) that might then lead to an allergic reaction. When there is a suspected trigger to reactions we sometimes measure specific IgE antibodies to that trigger in a blood test. For example, if you have symptoms after having peanuts we will discuss testing for specific IgE to peanuts.
I have high Specific Ig E antibody levels. What does this mean?
Having raised specific IgE antibodies does not always mean you definitely have an allergy. For instance, people who do not have peanut allergies could have raised specific IgE to peanut! Similarly some people with allergy to peanuts may not have raised specific IgE to peanuts. People with eczema can have very high IgE antibody levels, leading to falsely high specific IgE antibodies, making the interpretation of these results very difficult.
For these reasons, it is very important that specific IgE antibody tests are requested only when there is a clinical suspicion of reactions typical of IgE-mediated allergy. Specific IgE antibody test results also need to be interpreted with caution by experienced clinicians.
My doctor mentioned to me about genetic testing. What is a gene?
Each cell in our body contains “genes” inherited from our parents. Genes are made of a chemical called DNA, and they act as a “recipe book” that makes us who we are as individuals. Sometimes, genes can have spelling mistakes in the DNA. When this happens, the instruction in the “recipe book” can sometimes change and affect our health.
Since genes are passed on from one generation to the next, genetic disorders often run in families.
Genetic testing
Genetic testing is sometimes requested to assess if an immune problem is due to known mistakes in the genes involved in the development of the immune system. Your immunologist will discuss this with you in more detail if relevant and describe the risks and benefits of genetic tests.
What to expect from your immunology Annual Review
Patients with diagnosed immunodeficiency are usually followed up once a year, including an annual review of their diagnosis and ongoing treatment. Questions asked at the annual review will centre around the frequency of infections and possible complications of the immunodeficiency. Your immunologist will also review ongoing treatment and side effects. A physical examination is often done as part of this assessment.
Following this, changes may be made to your treatment. If any changes are considered, these will be discussed fully with you including risks and benefits. If you are on immunoglobulin replacement therapy or C1 inhibitor replacement, your immunologist will discuss continuation of these and obtain your consent for further treatment for a year.
A specialist nurse will usually be present and will review any issues or questions you may have with home therapy and deliveries.
Do I need to bring anything for my immunology annual review?
To maximise the benefit of your annual review, it is recommended that you bring:
- an up to date list of your medications
- discharge or clinic letters and investigation reports from other departments you attend
- tests detailing microbiology results from any infections
- any diaries you may have been advised to keep (for example to detail infection frequency, episodes of swelling and treatments given). Your immunologist may have recommended using an online diary which can help to keep all this information in an accessible place. There are also diaries you can download and complete on a computer or print to complete on paper. Further details are on the diaries page here.
- please also bring a reminder list of questions you want to ask to your doctor or specialist nurse so that you don’t forget to ask during your clinic appointment.